Air traffic control systems track positions and velocities of aircraft and help prevent aircraft collisions. Air traffic control has traditionally been based on radar surveillance, supplemented more recently with cooperative radio surveillance techniques. Cooperative radio surveillance includes automatic dependent surveillance broadcast (ADS-B) technology. An aircraft's ADS-B unit includes an ADS-B compatible transmitter and/or receiver, typically operating at a Mode S band at 1,090 megahertz (MHz). The ADS-B transmitting and receiving functions are individually referred to as ADS-B Out and ADS-B In, respectively, and different requirements or standards may be applicable to ADS-B Out and ADS-B In. A particular aircraft may transmit ADS-B Out messages that include specific data (further denoted as ADS-B data), and which may be received by ground-based Air Traffic Control (ATC) stations and by other aircraft. ADS-B data may include aircraft position and velocity based on GPS, position data accuracy, aircraft identification, barometric altitude, and other data. The particular aircraft may automatically transmit ADS-B messages at a specific broadcast rate. Each ADS-B message includes a preamble and a data block. ADS-B data may be encoded into 112 bits (message data) that may be conveyed by ADS-B message data block. The particular aircraft may receive ADS-B Out messages from other aircraft in its vicinity. The aircraft's ADS-B system may make data from ADS-B messages received from other aircraft available for other systems or applications on the aircraft, such as traffic computer and display systems.
Air traffic has been increasing over the years, such that some airports now frequently have crowded air traffic. Crowded air traffic translates to a congested communication environment, with often large numbers of aircraft within range and sending ADS-B Out messages, creating a high likelihood of frequent overlap between ADS-B messages. Frequent overlap between ADS-B messages may lead to failure to decode and receive a substantial number of ADS-B messages and may degrade the performance of any applications that use ADS-B message data, which may include applications involved in situational awareness, collision avoidance, and aircraft separation management, for example.